fix: clear TaskLane on chat switch and remove double border

- Reset TaskLane state in handleNewChat and selectChat
- Conditionally remove chat input top border when TaskLane is open

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

frontend/src/pages/AssistantChatPage.tsx

@@ -4,12 +4,16 @@ import { Sparkles, Send, Loader2, Flag, MessageSquare, Paperclip, Terminal, X, R
 import { cn } from '@/lib/utils'
 import { uploadsApi } from '@/api/uploads'
 import type { PendingUpload } from '@/types/upload'
+import type { ForkMetadata, ActionItem, QuestionItem } from '@/types/ai-session'
 import { PageMeta } from '@/components/common/PageMeta'
 import { aiSessionsApi } from '@/api/aiSessions'
+import { useBranching } from '@/hooks/useBranching'
+import { BranchMap } from '@/components/session/BranchMap'
 import { analytics } from '@/lib/analytics'
 import { toast } from '@/lib/toast'
 import { ChatSidebar } from '@/components/assistant/ChatSidebar'
 import { ChatMessage } from '@/components/assistant/ChatMessage'
+import { TaskLane } from '@/components/assistant/TaskLane'
 import { ConcludeSessionModal } from '@/components/assistant/ConcludeSessionModal'
 import type { ChatListItem, ConclusionOutcome } from '@/types/assistant-chat'
 import type { SuggestedFlow } from '@/types/copilot'
@@ -18,6 +22,9 @@ interface MessageWithMeta {
   role: 'user' | 'assistant'
   content: string
   suggestedFlows?: SuggestedFlow[]
+  fork?: ForkMetadata | null
+  actions?: ActionItem[] | null
+  questions?: QuestionItem[] | null
 }
 
 export default function AssistantChatPage() {
@@ -30,11 +37,15 @@ export default function AssistantChatPage() {
   const [input, setInput] = useState('')
   const [loading, setLoading] = useState(false)
   const [showConclude, setShowConclude] = useState(false)
+  const branching = useBranching()
   const [mobileSidebarOpen, setMobileSidebarOpen] = useState(false)
   const [showLogs, setShowLogs] = useState(false)
   const [logContent, setLogContent] = useState('')
   const [pendingUploads, setPendingUploads] = useState<PendingUpload[]>([])
   const [isDragOver, setIsDragOver] = useState(false)
+  const [activeQuestions, setActiveQuestions] = useState<QuestionItem[]>([])
+  const [activeActions, setActiveActions] = useState<ActionItem[]>([])
+  const [showTaskLane, setShowTaskLane] = useState(false)
   const messagesEndRef = useRef<HTMLDivElement>(null)
   const inputRef = useRef<HTMLTextAreaElement>(null)
   const fileInputRef = useRef<HTMLInputElement>(null)
@@ -88,7 +99,7 @@ export default function AssistantChatPage() {
         })
         setMessages(prev => [
           ...prev,
-          { role: 'assistant', content: response.content, suggestedFlows: response.suggested_flows },
+          { role: 'assistant', content: response.content, suggestedFlows: response.suggested_flows, fork: response.fork, actions: response.actions, questions: response.questions },
         ])
         setChats(prev =>
           prev.map(c =>
@@ -97,6 +108,17 @@ export default function AssistantChatPage() {
               : c
           )
         )
+        // Show task lane if AI sent questions or actions
+        if (response.fork && session.session_id) {
+          branching.loadBranches(session.session_id)
+        }
+        const hasQuestions = response.questions && response.questions.length > 0
+        const hasActions = response.actions && response.actions.length > 0
+        if (hasQuestions || hasActions) {
+          setActiveQuestions(response.questions || [])
+          setActiveActions(response.actions || [])
+          setShowTaskLane(true)
+        }
       } catch {
         toast.error('Failed to start AI conversation')
       } finally {
@@ -131,6 +153,10 @@ export default function AssistantChatPage() {
 
   const selectChat = useCallback(async (chatId: string) => {
     setActiveChatId(chatId)
+    // Clear TaskLane when switching chats
+    setShowTaskLane(false)
+    setActiveQuestions([])
+    setActiveActions([])
     try {
       const detail = await aiSessionsApi.getSession(chatId)
       setMessages(
@@ -161,6 +187,10 @@ export default function AssistantChatPage() {
       setChats(prev => [chatItem, ...prev])
       setActiveChatId(session.session_id)
       setMessages([])
+      // Clear TaskLane from previous session
+      setShowTaskLane(false)
+      setActiveQuestions([])
+      setActiveActions([])
     } catch {
       toast.error('Failed to create chat')
     }
@@ -184,6 +214,19 @@ export default function AssistantChatPage() {
     toast.info('Pin feature coming soon')
   }
 
+  const handleBranchSwitch = async (branchId: string) => {
+    if (!activeChatId || loading) return
+    const result = await branching.switchBranch(activeChatId, branchId)
+    if (!result) return
+
+    // Load the branch's conversation into the chat
+    const branchMessages: MessageWithMeta[] = (result.conversation_messages || []).map(m => ({
+      role: m.role as 'user' | 'assistant',
+      content: m.content,
+    }))
+    setMessages(branchMessages)
+  }
+
   const handleSend = async () => {
     if (!input.trim() || !activeChatId || loading) return
 
@@ -204,7 +247,7 @@ export default function AssistantChatPage() {
       analytics.aiFeatureUsed({ feature: 'assistant_chat' })
       setMessages(prev => [
         ...prev,
-        { role: 'assistant', content: response.content, suggestedFlows: response.suggested_flows },
+        { role: 'assistant', content: response.content, suggestedFlows: response.suggested_flows, fork: response.fork, actions: response.actions, questions: response.questions },
       ])
       setChats(prev =>
         prev.map(c =>
@@ -213,6 +256,18 @@ export default function AssistantChatPage() {
             : c
         )
       )
+      // Load branches if fork was created
+      if (response.fork && activeChatId) {
+        branching.loadBranches(activeChatId)
+      }
+      // Show task lane if AI sent questions or actions
+      const hasQuestions = response.questions && response.questions.length > 0
+      const hasActions = response.actions && response.actions.length > 0
+      if (hasQuestions || hasActions) {
+        setActiveQuestions(response.questions || [])
+        setActiveActions(response.actions || [])
+        setShowTaskLane(true)
+      }
     } catch {
       setMessages(prev => [
         ...prev,
@@ -224,6 +279,56 @@ export default function AssistantChatPage() {
     }
   }
 
+  const handleTaskSubmit = async (responses: Array<{ type: string; state: string; value: string; text?: string; label?: string }>) => {
+    if (!activeChatId || loading) return
+
+    // Format task responses into a structured message for the AI
+    const parts: string[] = []
+    for (const r of responses) {
+      const name = r.type === 'question' ? `Q: ${r.text}` : r.label || 'Check'
+      if (r.state === 'done' && r.value.trim()) {
+        parts.push(`**${name}:**\n\`\`\`\n${r.value.trim()}\n\`\`\``)
+      } else if (r.state === 'skipped') {
+        parts.push(`**${name}:** _(skipped)_`)
+      }
+    }
+    const userMessage = parts.join('\n\n')
+
+    // Close the task lane
+    setShowTaskLane(false)
+    setActiveQuestions([])
+    setActiveActions([])
+
+    setMessages(prev => [...prev, { role: 'user', content: userMessage }])
+    setLoading(true)
+
+    try {
+      const response = await aiSessionsApi.sendChatMessage(activeChatId, { message: userMessage })
+      setMessages(prev => [
+        ...prev,
+        { role: 'assistant', content: response.content, suggestedFlows: response.suggested_flows, fork: response.fork, actions: response.actions, questions: response.questions },
+      ])
+      if (response.fork && activeChatId) {
+        branching.loadBranches(activeChatId)
+      }
+      // Show task lane again if AI sends more tasks
+      const hasQuestions = response.questions && response.questions.length > 0
+      const hasActions = response.actions && response.actions.length > 0
+      if (hasQuestions || hasActions) {
+        setActiveQuestions(response.questions || [])
+        setActiveActions(response.actions || [])
+        setShowTaskLane(true)
+      }
+    } catch {
+      setMessages(prev => [
+        ...prev,
+        { role: 'assistant', content: 'Sorry, something went wrong processing your responses. Please try again.' },
+      ])
+    } finally {
+      setLoading(false)
+    }
+  }
+
   const handleConclude = async (outcome: ConclusionOutcome, _notes: string): Promise<string> => {
     if (!activeChatId) throw new Error('No active chat')
 
@@ -268,7 +373,7 @@ export default function AssistantChatPage() {
       const response = await aiSessionsApi.sendChatMessage(session.session_id, { message: resumePrompt })
       setMessages(prev => [
         ...prev,
-        { role: 'assistant', content: response.content, suggestedFlows: response.suggested_flows },
+        { role: 'assistant', content: response.content, suggestedFlows: response.suggested_flows, fork: response.fork, actions: response.actions, questions: response.questions },
       ])
       setChats(prev =>
         prev.map(c =>
@@ -277,6 +382,17 @@ export default function AssistantChatPage() {
             : c
         )
       )
+      // Show task lane if AI sent questions or actions
+      if (response.fork && session.session_id) {
+        branching.loadBranches(session.session_id)
+      }
+      const hasQuestions = response.questions && response.questions.length > 0
+      const hasActions = response.actions && response.actions.length > 0
+      if (hasQuestions || hasActions) {
+        setActiveQuestions(response.questions || [])
+        setActiveActions(response.actions || [])
+        setShowTaskLane(true)
+      }
     } catch {
       toast.error('Failed to create resume chat')
     } finally {
@@ -392,7 +508,8 @@ export default function AssistantChatPage() {
         />
       </div>
 
-      {/* Main chat area */}
+      {/* Main chat area + optional branch sidebar */}
+      <div className="flex-1 flex min-w-0">
       <div className="flex-1 flex flex-col min-w-0">
         {/* Mobile header with chat history toggle */}
         <div className="sm:hidden flex items-center gap-2 px-3 py-2 border-b border-border shrink-0">
@@ -452,7 +569,7 @@ export default function AssistantChatPage() {
             </div>
 
             {/* Rich Input */}
-            <div className="px-3 sm:px-6 py-3 shrink-0 border-t border-border">
+            <div className={cn("px-3 sm:px-6 py-3 shrink-0", !showTaskLane && "border-t border-border")}>
               <div
                 className="max-w-3xl mx-auto"
                 onDragOver={handleDragOver}
@@ -593,6 +710,22 @@ export default function AssistantChatPage() {
         )}
       </div>
 
+      {/* Task lane — slides in when AI sends questions or actions */}
+      {showTaskLane && (activeQuestions.length > 0 || activeActions.length > 0) && (
+        <TaskLane
+          questions={activeQuestions}
+          actions={activeActions}
+          onSubmit={handleTaskSubmit}
+          onClose={() => setShowTaskLane(false)}
+          loading={loading}
+        />
+      )}
+
+      {/* Branch map hidden — branching is now silent/background only.
+          Branches are tracked in the DB but not shown to the user.
+          The AI manages branch context internally. */}
+      </div>
+
       {/* Conclude Session Modal */}
       <ConcludeSessionModal
         isOpen={showConclude}